Analysis of resonant inelastic x-ray scattering in La2CuO4

We provide a semiquantitative explanation of a recent experiment on the resonant inelastic x-ray scattering (RIXS) in insulating cuprate La2CuO4 (Y.J. Kim et al., Phys. Rev. Lett. 89, 177003 (2002).). We show theoretically that there are three characteristic peaks in RIXS spectra, two of which are attributed to the charge transfer excitation and are reasonably assigned to those observed experimentally. The lowest energy peak has a relatively large dispersion ($\sim 0.8$ eV) and is suppressed near the zone corner (\pi, \pi), in agreement with the experiment. We stress that electron correlation is an essential factor for explaining the overall energy-momentum dependence of the RIXS spectra consistently.Comment: 5 pages, 5 figures, to be published in Phys. Rev.

Theory of L-edge resonant inelastic x-ray scattering for magnetic excitations in two-leg spin ladder

We study the magnetic excitation spectra of Cu L_{2,3}-edge resonant inelastic x-ray scattering (RIXS) from the spin-liquid ground state in two-leg spin ladder cuprates. Applying the projection method developed by the present authors, we have derived the formulas of the magnetic RIXS spectra, which are expressed by one- and two-spin correlation functions in the polarization changing and preserving channels, respectively. The one-spin correlation function includes both one- and two-triplon excitations and they are picked up separately by choosing rung wave vector -q_a=\pi and 0, respectively. An application to Sr_{14}Cu_{24}O_{41} reveals that the calculated RIXS spectrum captures well the dispersive behavior shown by the lower boundary of two-triplon continuum. By adjusting the geometrical configuration of the measurement, one-triplon dispersion around the zone center could be detectable in the RIXS experiment. The observed weak intensity in the higher energy region might be attributed to the two-spin correlation function, which could be detected more clearly at the M_{3}-edge RIXS spectra.Comment: 10 pages, 7 figures, Late